A tree chipper or wood chipper is a machine used for reducing wood, generally tree limbs or trunks, into smaller woodchips. Among the first commercially available, and still in production today, drum chippers employ mechanisms consisting of a large steel drum powered by a motor, usually by means of a belt. The drum includes a plurality of sharp edged blades or teeth disposed about its outer surface. The drum is mounted parallel to a hopper and spins towards an output chute. The drum also serves as the feed mechanism, drawing the material through as it chips it.
In order for a chipper to perform effectively, the blades need to be sharp. Therefore, when the blades are dull, the equipment is shut down and an operator must remove each bolted-on dull blade and replace them with new, sharp blades. The dull blades are sent to vendors for sharpening. This takes a significant amount of time and also requires that a full set of sharp blades be available.
There are currently few options for sharpening chipper blades without removing them from the drum, but each has significant drawbacks. One such option is the use of a manual blade dresser. This tool includes a sharpening stone mounted at a set angle within a handle. These tools may be used effectively in cases where the blades have not been significantly dulled. However, they require a significant amount of effort on the part of the user and do not produce uniform edges. Further, they expose the user to injury from contact with adjacent blades.
Another option is the “Bevel Buddy” tool sold by Precision Sharpening Devices, Inc. of Erie, Pa. This device consists of a guide that is mounted to a rotary tool, like those sold under the trademark “DREMEL”. In operation, the user aligns the guide with the blade and the rotating grinding wheel removes material from the flat back side of the blade. This poses significant drawbacks. First, grinding the flat backside of the blade is not effective at sharpening heavily dulled blades and is only useful at touching up lightly dulled blades. Second, the fact that the guide uses the beveled portion of the blade to guide the grinding wheel means that any lack of uniformity in the beveled surface, as can often occur when the blade is partially damaged, causes a lack of uniformity in the grind itself and a less effective cutting edge. Finally, the device is susceptible to variation based upon the angle that the user holds the tools, again resulting in non-uniform edges.
Therefore there is a need for a device that allows chipper blades to be sharpened quickly in the field without having to remove them from the drum, that does not require a significant amount of effort on the part of the user, that may be used to sharpen heavily dulled blades, that does not expose the user to injury from contact with adjacent blades, that produces uniform edges, and that sharpens the beveled side of the blade.